Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

readOnlyHint and openWorldHint already tell the agent this is a safe, external-facing read. The description adds only the list of aggregation dimensions, which is also present in the schema, and says nothing extra about result shape or constraints. Output schema exists, so return-value disclosure isn't needed.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

A single front-loaded sentence with no filler and the operation stated first. It is appropriately sized, though the parenthetical facet list is partly redundant with the schema.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With annotations covering safety, a full output schema, and 100% parameter documentation, the description only needs to convey purpose and routing; it does so adequately. It falls just short of complete by not clarifying how it relates to the sibling search/item tools.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline is 3. The description repeats the facet dimensions but omits run_id (which the schema's enum includes) and adds no syntax or interaction detail beyond what the schema documents.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific operation ('facet aggregation') over a specific resource ('BBB businesses dataset') and enumerates the available facet dimensions. It is clear what the tool does, though it doesn't explicitly name the sibling tools (datasets_bbb_businesses_search/item) it complements.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The phrase 'facet aggregation' implies this is for obtaining distribution counts rather than individual records, which distinguishes it in spirit from search/item siblings. However, there is no explicit when-to-use, when-not-to-use, or alternative-naming guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.